A manure storage tank in Italy's buffalo farming region likely played a role in a major salmonella outbreak in Europe, according to researchers.
In 2024, a significant outbreak of Salmonella Umbilo caused by contaminated products from Salerno in Italy was reported throughout the European Union. Subsequent inspections at the production site revealed improper handling of the manure storage tank.
Three buffalo farms were found within a 1 km radius, including the reservoir and contaminated greenhouses. Upon examination, buffalo calves were found to have intestinal symptoms. Fecal samples from these animals led to the isolation of Salmonella Umbilo, genomically linked to the multi-country outbreak, as well as other serotypes.
Manure tank problem
A severe public health alert between July and December 2024 resulted in cases in Germany, Austria, Denmark, Italy, Switzerland and the UK. More than 200 cases of infection and one death have been reported. Germany was hit the hardest with 118 cases.
The outbreak was epidemiologically linked to the consumption of arugula and organic baby spinach from Italy. Investigations by Italian authorities have identified the production site of the implicated vegetables in the province of Salerno in the Campania region, an area known for intensive buffalo farming. There are no national programs to control salmonellosis in ruminants.
Research published in the journal International Journal of Environmental Research and Public Health found that between November 2024 and January 2025, local and regional authorities conducted field surveys to assess potential sources of environmental contamination in the greenhouse area associated with the outbreak.
An inspection of the area led to the discovery of an unauthorized and poorly managed manure storage tank, apparently intended for a nearby cattle farm.
An open manure storage tank of unknown ownership posed a significant risk of overflowing into adjacent irrigation canals when filled to capacity. Due to poor management and during rainy periods, livestock waste from nearby farms could enter drainage systems, potentially introducing microbial pathogens into the agricultural environment. The scientists said the late collection of two samples from the manure tank could explain the negative microbiological results.
Positive aspects of buffalo
At the end of 2024, an epidemiological investigation by veterinarians at three buffalo farms within a 1 km radius of a manure storage tank identified buffalo calves with intestinal symptoms. Fecal tests confirmed outbreaks of salmonellosis in calves born in November and December.
Four buffalo calves tested positive for Salmonella Senftenberg. At the second facility, six calves tested positive for Salmonella Umbilo. On the third farm, six calves tested positive for Salmonella Livingston. These results have prompted targeted measures to control outbreaks and prevent spread to livestock, horticultural products and people.
The scientists also said that current datasets on open access platforms covering human cases, associated clinical complications, and genomic analysis of isolates from animals, food, feed and environmental samples are insufficient.
“The lack of comprehensive publicly available data severely limits the ability to reconstruct events leading to public health emergencies, understand epidemiological links between sectors, and reconcile and compare results from different laboratories and institutions,” they added.
“Ultimately, greater access to epidemiological and microbiological data can significantly improve the speed and efficiency of outbreak investigations, allowing the origins of epidemics to be quickly identified and chains of transmission to be immediately interrupted, thereby protecting the health of people, animals and the environment.”
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